In the manufacture of hollow containers such as glass flasks, the articles undergo a series of inspections and treatments as they move on conveyors from forming to filling, labeling and packing. For many such operations, for example, in annealing in a lehr, a large group of articles are treated simultaneously while they are arrayed in rows and columns on a wide belt, and their precise orientation is not particularly important. In other operations, however, they are treated or handled sequentially while moving in single-file order on a conveyor.
In some cases it is necessary that articles which are non-symmetrical about a vertical axis, such as flasks, which traditionally are concave-convex in section, be oriented consistently so as to all face the same direction. Proper orientation of flasks is particularly important in filling and labeling, because the equipment usually employed for that purpose does not accommodate improperly oriented flasks and will frequently break or mislabel them.
The orientation of a flask on a production line is initially determined, of course, by the orientation of the mold wherein it is formed. However, subsequent transfers and handling may turn some of the flasks by 180.degree. so that they are oriented reversely from the others.